1. Field of the Invention
This invention relates generally to the preparation of printing pattern films, and more particularly to a method of automatically preparing color separation printing pattern films from a multi-colored original design by means of digital logic.
In the additive printing process, a multi-colored original design is usually reduced beforehand into a number of black and white pattern films each containing a pattern of one color for use as color separation pattern films. The preparation of the color separation pattern films has thus far relied on manual labor of a skilled tracer who can translate the original design into an industrially useful form through precise analysis of the original design. The tracer's work usually requires strict recognition of colors and patterns constituting the original design in order to correct and clarify the imperfections or obscurities which might be contained in the original when viewed as an industrial design as well as modification and conversion of constituent patterns to adapt them to confirm to various conditions imposed by a particular printing machine, method or by a particular nature of cloth to be printed.
Typical examples of the defects of the original in an industrial design include unevenness in color and touch, undesirable overlapping of two different colors on the borders thereof, fine lines non-uniform in thickness, obscure color borders and the like. On the other hand, the examples of pattern modifications and conversions for adaptation to actual printing include pattern linking reduction or contraction of heavy color pattern areas and enlargement of light color pattern areas and separation of fine lines of a ground or base color.
As mentioned hereinbefore, it has been the conventional practice of the tracers to abstract the original patterns of the respective original colors on separate mat sheets as black and white images. The tracer's work requires meticulous skills and imposes physical and mental strains since the tracer has to work his eyes hard in recognizing and correcting imperfections such as uneven and overlapped colors and also in modifying the design to conform to the requirements arising from the actual printing process, resulting in work extremely low in efficiency.
On the other hand, there has been proposed a method of separating colors of an original design and forming patterns of the respective colors in black and white on a photosensitive film in a completely automated process with use of an analog computer. However, with the method using analog units, it is difficult to correct imperfections which might be in the original design, such as uneven colors and obscure pattern configurations, fine lines lacking uniformity in width, and to mend the pattern modifications including reductions and enlargements of particular patterns and divisions of patterns of the same color, which are usually required in the practical printing process to compensate for dye bleeding and ensure pattern linkage. The prior art method just mentioned usually employs a discharge tube as a light source in producing color separation patterns on photosensitive films. However, this is disadvantageous as the image pattern which is ultimately produced on the photosensitive film is inferior in sharpness and it is difficult to process image patterns at a high speed.
As will be gathered from the foregoing description, the color separation pattern films prepared by the existing automatic processing systems still contain latent factors which do not conform to actual printing conditions or requirements, so that it is necessary to station an operator who has high technical knowledge on the color separating pattern modifications in order to effect manually the necessary corrections and modifications at a suitable stage.